Safety headgear

ABSTRACT

The present specification protective headgear including a unitary shell ( 1 ) having a bell shape with a non-uniform thickness, the shell being of sufficient size to enclose at least an upper part of the wearer&#39;s skull, the shell having an upper crown portion ( 6 ) with a central crown area ( 2 ) and a surrounding outer crown area ( 3 ), the shell further including a depending circumferential wall which has an upper wall area ( 4 ) adjacent to the outer crown area ( 2 ) and a lower wall area ( 5 ), the lower wall area ( 5 ) having a wall thickness generally greater than the wall thickness of said upper wall area ( 4 ), and the central crown area ( 2 ) having a wall thickness generally greater than the wall thickness of said outer crown area ( 3 ), the headgear further including a support system ( 9 ) attached to the lower wall area(s) of the shell ( 1 ) in a manner whereby no less than 5 mm space is maintained between the wearer&#39;s skull and an inside surface of the shell ( 1 ).

[0001] The present invention relates to headgear suitable for activitiesthat require head protection. In particular the present inventionrelates to headgear for use during work or recreational activities.

[0002] The invention will be described with particular reference toheadgear suitable for use during recreational activities such as horseriding, however the invention is not exclusively limited to thisapplication and is suitable for protecting a wearer's head during a widerange of activities. For example, the headgear is also suitable forindustrial activities such as construction work and mining and can beused by security guards and police for protection against assault.

[0003] In particular the headgear of the present invention can beincluded in a new hat during manufacture or incorporated into anexisting hat.

[0004] Head protection during recreational and work related activitiesis sufficiently important that dedicated national headgear standardsexist for construction, bicycle and equestrian helmets.

[0005] Horse riding is typical of a sport that leads to many thousandsof accidents each year. For example, in the United States over 180,000people were hospitalised in 1994 as a result of horse riding relatedaccidents. A large proportion of the resulting injuries were headinjuries, most of which could have been avoided by wearing a helmet.

[0006] Horse riders commonly wear headgear of one sort or another,either for protection or as a fashion item. Riders who wear headgear forprotection usually choose helmets to avoid injuries caused by strikingtheir head on the ground or an obstacle during a fall. However manyriders wear headgear purely as a fashion item. The fashion icon ofWestern riding, particularly in North America and Australia, is the“cowboy” hat or Akubra. This type of hat provides protection from thesun, but does not provide any protection against injury due to a fall.In Western Europe, riders are more likely to wear a riding cap, whichconsists of a close fitting, hard, almost hemispherical shell coveredwith material such as velvet. Riding caps are traditional fashion itemsand the hard shell provides some head protection in the event of a fall.

[0007] The majority of protective headgear for recreational activitiescomprise helmets having a rigid hemispherical shell, lined with expandedpolystyrene or the like, that fit closely around the wearer's head.Typically these helmets are very bulky, and as much as 3 or 4centimetres thick due to the relatively large amount of polystyrenerequired to adequately protect the wearer's head.

[0008] Despite the desirability of head protection, the wearing of acertified headgear during activities such as horse riding or bicycleriding is not compulsory in most countries. Many riders ignore safetyrisks and do not wear headgear such as protective helmets because theyare bulky, hot and unattractive. Even in industries where the wearing ofa protective helmet is supposed to be compulsory, workers often discardtheir helmets because a bulky helmet can inhibit movement and heatgenerated can cause excessive sweating and headaches. These problems canlead to a wearer having an accident, thus defeating the purpose ofwearing a protective helmet.

[0009] In the past, efforts have been made to overcome the problem ofexcess heat being generated and trapped inside headgear such asprotective helmets. For example, U.S. Pat. No. 5,718,004 relates to aprotective equestrian helmet incorporating a vent device in the crown totransmit cool air from outside into the protective helmet and to allowescape of heated air from inside the helmet. Furthermore, UK patentapplication no. 2,240,255 relates to a protective helmet comprising ashell supported against the user's head by a number of spaced resilientpads to reduce heat build up.

[0010] The aesthetic or fashion aspect of headgear should not beunderestimated and protective helmets are often disregarded in favour ofmore attractive headgear. The appearance of a horse rider can be ofparamount importance, such as in dressage events. For many stockmen, itwould be unthinkable to wear a protective helmet instead of thetraditional Akubra. Furthermore, unlike a helmet, an Akubra has a widebrim to provide protection from the sun and this is important both forrecreational riders, and professional riders such as stockmen who spendtheir working days on horseback under the sun.

[0011] In order to overcome these problems, attempts have been made inthe past to provide a combination of a broad brim hat with existingprotective helmets certified to satisfactory safety standards. Anexample of this is provided in Australian patent application no.12437/97 which relates to a protective cover (hat) within which can belocated a helmet.

[0012] However as mentioned above, protective helmets commonly include arelatively large quantity of expanded polystyrene and are 3 or 4 cmthick. Most of the attempts to provide a combination of an attractivehat with a protective helmet have been too simplistic, with theappearance of the hat ruined by a helmet that either bulges above thebrim or is visible below it. Furthermore, the large size of the helmetcauses the crown of the hat to be grossly enlarged and out of proportionto the brim. Accordingly these types of helmets have failed to grasp amarket share.

[0013] It has now been found that a headgear can be provided whichprovides improved head protection.

[0014] Accordingly, the present invention provides headgear forprotecting a wearer's skull including a generally bell shaped shell ofnon-uniform thickness for enclosing at least an upper part of thewearer's skull, the shell having an upper crown portion with a dependingcircumferential wall area which has an upper wall area adjacent to theupper crown portion and a lower wall area, said lower wall area having awall thickness generally greater than a wall thickness of said upperwall area, and a support system attached to the lower wall area of theshell, wherein in normal use the support system rests on the wearer'sskull and maintains an inside surface of the shell at least apredetermined distance from the wearer's skull. Preferably the crownportion has a wall thickness generally greater than a zone of said shellbetween said upper crown portion and said upper wall area. Convenientlythe predetermined distance is no less than 5 mm.

[0015] Preferably the aforesaid zone has a thickness less than thethickness of said upper wall area. Preferably the thickness of the shellmerges smoothly between the lower wall area and the upper crown portion.

[0016] In one preferred arrangement, the upper crown portion includes acentral crown area and a surrounding outer crown area with the centralcrown area having a thickness greater than that of the outer crown area.The aforesaid zone may be formed by the outer crown area, by a portionof the outer crown area or by a separate portion between the outer crownarea and the upper wall area.

[0017] In accordance with a second aspect, the present inventionprovides a hat having an outer covering of a flexible sheet material, agenerally bell shaped shell moulded from a high impact resistantmaterial, the shell having an upper crown portion with a dependingcircumferential wall area adjacent to the upper crown portion, the shellbeing configured to fit within said outer covering, and a support systemattached to a lower wall area of the shell, wherein in normal use, thesystem rests on the wearer's skull and maintains an inside surface ofthe shell at least a predetermined distance from the wearer's skull.

[0018] Preferred features of this aspect of the invention may be asdefined in claims 20 to 25 as annexed hereto which are hereby made partof the disclosure of this specification.

[0019] According to a still further aspect, the present inventionprovides headgear for protecting a wearer's skull including:

[0020] a generally bell-shaped shell of non-uniform thickness forenclosing at least an upper part of the wearer's skull, the shell havinga crown surrounded by a wall, the thickness of the crown being between2.0+or −0.1 mm and 3.4+or −0.1 mm and the thickness of the wall beingbetween 2.6+or −0.1 mm and 3.8+or −0.1 mm, and a support system attachedto a lower region of the wall of the shell,

[0021] wherein in normal use the support system rests on the wearer'sskull and maintains an inside surface of the shell no less than 5 mmfrom the wearer's skull.

[0022] An advantage of the headgear of the present invention is that theconstruction is sufficiently compact that it can be inserted into anexisting hat, thus combining a fashionable appearance with practicaladvantages. Alternatively the headgear may be incorporated into a newhat during manufacture.

[0023] In the event of accident the shell is the first part of theheadgear to strike a solid object such as the ground or a tree, post orthe like. This could happen, for example, when a rider is thrown ordismounted from a horse or falls from a bicycle. The shell musttherefore protect the wearer's head against impact injury includingpenetration, which would cause major brain injuries and potentiallyprove to be fatal.

[0024] In the past, protective headgear commonly included a shell ofgenerally constant thickness. It has now been found that a shell ofnon-uniform thickness is more efficient in protecting a wearer and isfar more efficient at absorbing impact and shock energy than a shell ofeven thickness. Without wishing to be bound by theory, it is believedthat the shell of the present invention absorbs part of the impactenergy by elastic deformation and/or by crumpling of one or more areas,sufficient to avoid contact between the shell and the wearer's skull,but large enough to avoid deceleration injury.

[0025] The shell is of generally bell-shape that is a shape thatconforms generally to the shape of the upper part of a user's skull. Forexample the shell may be hemispherical. Typically, the shell is of ashape that encloses virtually all of the frontal and parietal bones ofthe wearer's skull, and at least a part of the occipital, temporal andspheroid bones. The uppermost or crown portion of the shell is locatedadjacent the pre-central and post-central gyrus of the wearer's brainand thus protects the premotor, primary motor and general sensory areasof brain function.

[0026] In a preferred embodiment, the shell comprises an uppermost crowndefined by a wall, the crown and wall being of non-uniform thickness.Preferably, the thickness of the crown is between 2.2+or −0.1 mm and3.2+or −0.1 mm. Preferably, the thickness of the wall is between 2.8+or−0.1 mm and 3.6+or −0.1 mm.

[0027] The crown preferably has a central crown area defined by an outercrown area, and preferably the wall has an upper wall area, which isadjacent a lower wall area, each of the areas being of differentthickness to the adjacent area(s).

[0028] Typically the central crown area is between 2.4+or −0.1 mm and3.4+or −0.1 mm thick, preferably between 2.8+or −0.1 mm and 3.3+or −0.1mm, more preferably between 3.1+or −0.1 mm and 3.3+or −0.1 mm. Thecentral crown area may be of any convenient conformation. For example,the central crown area may be flat, convex or concave. In a particularlypreferred embodiment, the central crown area is generally depressedrelative to the surrounding outer crown area and includes a centrallylocated dome (outwardly convex).

[0029] Typically, the central crown area is enclosed by the outer crownarea. Preferably the outer crown area is between 2.0+or −0.1 mm and2.4+or 0.1 mm thick, preferably between 2.1+or −0.1 mm and 2.3+or −0.1mm. In a preferred embodiment the outer crown area is raised relative tothe central crown, forming a continuous ridge around the central crownarea.

[0030] Typically the outer crown area is adjacent the upper wall area,and the upper wall area is preferably between 2.6+or −0.1 mm and 3.0+or−0.1 mm thick, or more preferably between 2.7+or −0.1 mm and 2.9+or −0.1mm.

[0031] Typically the upper wall area is also adjacent a lower wall area.The lower wall area is between 3.4+or −0.1 mm and 3.8+or −0.1 mm thick,more preferably between 3.5+or −0.1 mm and 3.7+or −0.1 mm. The lowerwall area will typically terminate with at an edge, or a flange forminga brim.

[0032] The shell may be of unitary construction, the thickness of theshell changing progressively from one area to another. Preferably theshell is made of highly impact-resistant material, including plastics orpolymers such as polycarbonate, ABS or an alloy of these two materials.The shell may be made by any convenient method such as injection moldingor press molding.

[0033] The support system in normal use maintains the inside surface ofthe shell no less than 5 mm from the wearer's skull. The support systemmay comprise strapping, webbing, netting or the like. Typically, thesupport system comprises a band that encircles the wearer's head at theupper forehead level plus three straps, each of which passes of thecrown of the user's head, the ends being attached to the band.Typically, the band is of adjustable length so that the wearer cancontrol the fit.

[0034] Where straps are used, typically their width is between 15 and 25mm, preferably 25 mm for good load distribution and comfort. The strapscan be made of the material used for seat belt construction, whichmaterial is known to have excellent shock absorbing characteristics.

[0035] The band may be held in place at the lower wall area of the shellby any convenient means. Preferably the band is held in place byanchorage devices, each anchorage device having a first end located in arecess in the band and a second end located correspondingly locatedrecess in the shell. Typically, the ends can be elastically deformed tofit into the recesses. The anchorage device may perform the function ofa spacer, maintaining the inside surface of the shell at least 5 mm fromthe wearer's skull. In a preferred embodiment, the headgear includesfour anchorage devices, located adjacent and on either side of thewearer's ears.

[0036] Again, without wishing to be bound by theory, it is believe thatin the case of significant impact to the shell, energy not absorbed bythe shell is transmitted to the support system. Furthermore, the supportsystem will be stretched by the impact load, absorbing the remainder ofthe energy by elastic or even plastic deformation, depending on theseverity of the impact.

[0037] Optionally, the headgear will also incorporate a chin strapattached to the outer shell by any convenient means, such as studs oneach side of the wearer's ears. The shell may be reinforced or thickenedat or adjacent the attachment point, because these areas are likely tosuffer stress concentration during an impact. The chin strap assists inmaintaining the hat in the correct position during a front, side or rearimpact. The chin strap can be equipped with a quick fastening system foreasy length adjustment. The chin strap may be made of any convenientmaterial.

[0038] Optionally, a solid impact absorber may be attached to the insidesurface of the shell, preferably adjacent the central crown area of theshell. Typically, when an impact occurs, the solid impact absorber willabsorb some of the impact energy by deformation. The solid impactabsorber may assist in maintaining the inside surface of the shell atleast 5 mm from the wearer's skull. Typically, the solid impact absorberis expanded polystyrene foam having a density between about 80 and 95g/l, preferably 90 g/l.

[0039] Preferably there is a continuous ventilation path between thefront and rear of the headgear. The 5 mm or more gap between the insideof the shell and the support system may define a suitable ventilationpath. Head motion during activities such as horse riding, or bicycleriding creates an increase in air pressure in front of the rider's headand a reduction in air pressure behind the rider's head. Thus externalair is forced under the leading edge of the shell, along the ventilationpath and out the following edge of the shell. Vent holes in the frontand back of the shell may facilitate air flow. In a further possibleembodiment, a series of vent holes may be provided spaced around theperiphery of the shell at an upper level of the side wall slightly belowthe trough level between the inner and outer crown regions of the shell.The vent openings may be spaced about by 40 to 50 mm.

[0040] Optionally, the headgear includes comfort padding, provided thatthe padding does not interfere with the operation of the support system.The comfort padding may optimise both comfort and fit. Typically thecomfort padding is in the form of soft pads that can be attached to theinside of the hat using Velcro™.

[0041] Headgear according to the invention of the present invention canbe made to conform to both Australian Standard AS 1801-1997“Occupational Protective Helmets” and US Standard F 1163-95.

[0042] The invention will now be further described with reference to thefollowing drawings that depict non-limiting preferred embodiments ofheadgear of the present invention in which:

[0043]FIG. 1 is a perspective view of the shell of one embodiment of theheadgear of the present invention,

[0044]FIG. 1A is a partially longitudinal section (along line A-A ofFIG. 1) side view of the shell shown in FIG. 1;

[0045]FIG. 1B is a partially transverse section (along line B-B ofFIG. 1) front view of the shell shown in FIG. 1;

[0046]FIG. 2 is a plan view of an adjustable head engaging band used ina support system for headgear according to this invention;

[0047]FIG. 2A is a sectional view along line A-A of FIG. 2;

[0048]FIG. 3 is a perspective view of one embodiment of an anchor devicefor securing together the shell and support system of the headgear ofthe present invention,

[0049]FIG. 3A is a section view showing the anchor device of FIG. 3 in aposition of use;

[0050]FIG. 4 is a plan view of an adjustable head engaging band similarto FIG. 2. but showing an alternative means of connecting the shellthereto;

[0051]FIG. 4A is a section view along line A-A of FIG. 4:

[0052]FIG. 5 shows the shell of FIG. 1, the support system including theband of FIG. 2 and the anchor device of FIG. 3 in combination to formone preferred embodiment of the headgear of the present Invention;

[0053]FIG. 6A Is a side view of the shell of another embodiment of theheadgear of the present invention with the inner features of the shellshown dotted in “ghost form”;

[0054]FIG. 6B is a front view of the shell of FIG. 6A

[0055]FIG. 6C is a top view of the shell of FIG. 6A; and

[0056]FIG. 6D Is a transverse section (along line A-A of FIG. 6C) frontview of the shell of FIG. 6A.

[0057]FIG. 1 is a perspective view of one embodiment of the shell (1) ofthe headgear showing four areas of different thickness. The shell isgenerally bell-shaped, of a size and shape that encloses virtually allof the frontal and parietal bones of a wearer's skull, and at least apart of the occipital, temporal and spheroid bones. The crown area isformed by a central crown area (2) and an outer crown area (3) which arelocated adjacent the pre-central and post-central gyrus of the wearer'sbrain.

[0058] In the illustrated embodiment, the central crown area (2) isdepressed relative to the surrounding outer crown area (3) and includesa raised dome section (7) in the centre and a trough section (8) betweenthe raised dome section (7) and the outer crown area (3). The centralcrown area (2) may be 3.2+/−0.1 mm thick with the surrounding outercrown area (3). In the illustrated embodiment forming a continuous ridgewhich may be 2.2+/−0.1 mm thick.

[0059] The shape of the crown area (2) and (3) may vary depending on theshape of the hat ultimately to be constructed. For example, the outercrown area (3) may have a greater radial width with the central crownarea simply forming a depression. In other embodiments fore and aftextending spaced ridges may be formed in the crown area.

[0060] Below the crown area (2) and (3) an upper wall area (4) Isprovided encircling the perimeter of the outer crown. The upper wallarea (4) may be 2.8+/−0.1 mm thick.

[0061] A lower wall area (5) encircles the perimeter of the upper walland terminates at a lower edge of the shell. The lower wall area may be3.6+/−0.1 mm thick. The lower wall area (5) may be oval in shape whenviewed in plan having a major dimension of 211+/−2.0 mm in length. Theminor dimension of the oval shape may have a dimension of 176+/−1.5 mmin length.

[0062] A first embodiment of the support system (9) for the headgear isbest illustrated in FIGS. 2, 2A, 3, 3A, and 5 of the accompanyingdrawings. The support system (9) includes an adjustable head band (10)intended to encircle the upper part of the users skull at the level ofthe upper forehead, together with three (15 mm wide) straps (11 a, 11 b,11 c) each of which passes over the crown of the user's head crossingeach other as they pass over the crown. The ends of each strap (11 a, 11b, 11 c) are attached to the head band (10) by passing through slots(30) provided for this purpose. The head band (10) includes a first end(31) having guide formations (32) to receive a second end (33) of theband (10) in a slidable adjacent configuration. The first end (31) alsoincludes a plurality of projections (34) each of which is adapted to bereceived in one of a plurality of apertures (35) formed in the secondend (33) whereby the band (10) is adjustable in length for differenthead sizes. The end regions (31) and (33) are angled downwardly relativeto a central region (36) of the band to provide a lower support towardsthe rear of the wearer's head as shown in FIG. 5.

[0063]FIG. 3 is a perspective view of one embodiment of an anchor device(14) for securing together the shell (1) and support system (9) of theheadgear of the present invention. The anchor device (14) includes ashaft (16) having a centrally located flange (18), the ends of the shaftterminating in heads or conical shaped bosses (15 a, 15 b). The shaft(16) is conveniently rectangular in cross-section having a width equalto the diameter of the heads (15 a, 15 b).

[0064]FIG. 3A depicts the anchor device (14) of FIG. 3 in use. One endof the anchorage device (15 a) is located adjacent the shell (1) whilethe other end (15 b) located adjacent the band (10) of the supportdevice (9). Intermediate the two ends of the anchorage device is theflange (18) that maintains the relative positions of the shell (16) andthe band (10) such that the distance A-A′ is preferably never less than5 mm. That is, the anchorage device (14) performs the additionalfunction of a spacer, maintaining the inside surface of the shell atleast 5 mm from the wearer's skull.

[0065] The anchor devices (14) are conveniently secured to the shell (1)and th head band (10) by engagement with suitably positioned key holeapertures (37) provided in the shell (1) and (38) in the band (10). Eachof the keyhole apertures has a larger opening (39) through which thehead regions (15 a, 15 b) may pass and a narrower slot region (40)engagable with the shaft regions (16) of the anchor devices (14) in use.Conveniently in the shell (1), the larger openings (39) on both sides ofthe shell face towards a forward end (41) of the shell.

[0066] Referring now to FIGS. 4 and 4A, a modified support device (9′)is shown including an adjustable head band (10) similar to that which Isshown in FIG. 2. Like features have been give the same referencenumerals and are therefore not further described hereinafter. In thismodified support device (9′) anchor devices (50) are provided but whichare integrally moulded with the head band (10) rather than beingseparate therefrom. The anchor devices (50) include a circular disc orhead (51) supported on a web (52) that spans a circular opening (53) inthe head band (10). The web (52) is integrally formed with the band (10)on opposed sides of the opening (53). The circular disc or head (51)engages with the keyhole openings (37) in the shell (1) in the same wayas the heads (15 a) of the separate anchor devices (14) of FIG. 2. Theminimum spacing A-A′ between the wearer's skull and the inside surfaceof the shell (1) is maintained by a plurality of spaced projections (54)also integrally formed with the band (10). This minimum distance isdesirably at least 5 mm.

[0067]FIG. 5 illustrates schematically the shell (1) of FIG. 1, thesupport system (9) including a plurality of anchor devices (14) or (50)in combination to form one preferred embodiment of headgear of thepresent invention. The headgear may be covered by a cover (42) in thestyle of a wide brimmed hat or in fact any other style. Conveniently theshape of the crown region of the shell (1) approximates the shape of thecrown of the hat cover (42).

[0068]FIGS. 6A to 6C Illustrate a variation of the shell of FIG. 1 towhich a 10 mm flange has been added around the base of the shell. Theflange serves to increase the stiffness of the shell. A second, minor,variation is the elevation of the raised dome of the central crown areato approximately the same height as the outer crown area.

EXPERIMENTAL

[0069] The shell depicted in FIG. 1 was tested using computer simulationfor compliance under three separate testing regimes. A comparativeexample was also tested, the comparative example comprising a shell ofuniform thickness of 2.8 mm, and having a simple depression in the crown(but no dome as per the headgear of FIG. 1). For the purposes of thesimulation the shell of FIG. 1 and the comparative example were deemedto be manufactured

[0070] from CYCOLOY C1200 polymer. (CYCOLOY C1200 is a trade mark ofGeneral Electric Corp.)

[0071] The comparative example was modeled in IGES file format and theheadgear of FIG. 1 was created as a full thickness, full revolutionmodel by modification within Rhino and Solid Edge V8 software by LeapAustralia Pty Ltd. For the purpose of finite element analysis, the IGESfile and later files based on it were imported into ANSYS and a finiteelement mesh was generated from them.

[0072] Test 1

[0073] The shell of FIG. 1 and the comparative example were testedaccording to the “Resistance to Penetration” regime of AustralianStandard 1801-1997, Clause 4.6. This regime requires that a 3 kg pointedstriker with 60 degree included angle and 0.5 mm tip radius is droppedfrom 1 metre to impact on the shell being tested within 50 mm of the topor centre of the crown. The minimum safety requirement is that thestriker under this free fall should not hit a head form located in theheadgear to simulate a human head.

[0074] The shell was constrained at four points around its edge tosimulate the support system attachment that connects the support systemto the head form. Nodes in these regions were fully constrained in alldegrees of freedom. For the analysis, the striker geometry was createdas per the specifications and modeled as a rigid body.

[0075] Both the comparative example and the helmet of FIG. 1 satisfiedthe requirements of AS 1801-1997. However, the penetration depth of thestriker into the shell of the present invention was far less that thepenetration depth into the comparative example.

[0076] Test 2

[0077] The shell of FIG. 1 and the comparative example were testedaccording to the “Shock Absorption Test” of Australian Standard1801-1997, Clause 4.6. In this test a 5 kg, 50 mm spherical striker isallowed to fall freely onto the shell with energy of 50 J. The minimumsafety requirement is that the deceleration of the striker must notexceed 980 m/s² and the force transmitted to a head form located in theshell must not exceed 5 kn.

[0078] The shells being tested were constrained at four points aroundtheir edge to simulate the support system attachment that connects thesupport system to the head form. Nodes in these regions were fullyconstrained in all degrees of freedom.

[0079] The comparative example did not comply with AS 1801-1997; thatis, the deceleration of the striker exceeded 980 m/s² indicatinginsufficient shock absorption.

[0080] By comparison, the shell of FIG. 1 satisfied the requirement ofAS 1801-1997 with a maximum deceleration of the striker of approximately815 m/s 2 which is less than the maximum value of 980 m/s² required bythe standard. It is believed that when the striker contacts the shell,energy is absorbed by the shell due to collapse of the raised dome inthe central crown area, and “crumpling” of the outer crown area.

[0081] Test 3

[0082] The shell of FIG. 1 and the comparative example were testedaccording to the “Stiffness Test” of Australian Standard 1801-1997,Clause 4.5. In this test a 90 N compressive load is applied to theshell. The safety requirement is that the shell does not deform morethan 15 mm measured 8 to 10 seconds after the load is applied.

[0083] For the Stiffness Test, the shell was fixed on one side tosimulate the loading face of the compression-testing machine defined inAS 1801-1997. A load was then applied to an identically sized area onthe opposite face of the helmet to simulate compressive loading.

[0084] The comparative example did not meet the requirements of AS1801-1997. Under compressive loading for the stiffness test, thecomparative example was too flexible and deformed inwardly beyond theacceptable 15 mm limit.

[0085] By comparison, the shell of FIG. 1 satisfied the requirement ofAS 1801-1997 with deformation of less than the 15 mm limit required bythe standard. It is believed that the thickness of the lower wall regioncontributed to the better performance.

[0086] While the foregoing describes preferred embodiments of theinvention, various modification scan be included without departing fromthe spirit and scope of the invention.

The claims defining the invention are as follows:
 1. Headgear forprotecting a wearer's skull including: a generally bell-shaped shell ofnon-uniform thickness for enclosing at least an upper part of thewearer's skull, the shell having a crown surrounded by a wall, thethickness of the crown being between 2.0+or −0.1 mm and 3.4+or −0.1 mmand the thickness of the wall being between 2.6+or −0.1 mm and 3.8+or−0.1 mm, and a support system attached to a lower region of the wall ofthe shell, wherein in normal use the support system rests on thewearer's skull and maintains an inside surface of the shell at least apredetermined distance from the wearer's skull.
 2. Headgear according toclaim 1 wherein the predetermined distance is no less than 5 mm. 3.Headgear according to claim 1 or claim 2 wherein the crown has a centralcrown area surrounded by an outer crown area, and the wall has an upperwall area, which is adjacent a lower wall area, each of the areas beingof different thickness to the adjacent area(s).
 4. Headgear according toclaim 2 wherein the central crown area is between 2.4+or −0.1 mm and3.4+or −0.1 mm, the outer crown area is between 2.0+or −0.1 mm and2.4+or −0.1 mm thick, the upper wall area is between 2.6+or −0.1 mm and3.0+or −0.1 mm thick and the lower wall area is between 3.4+or −0.1 mmand 3.8+or −0.1 mm thick.
 5. Headgear according to claim 3 or claim 4wherein both the central crown area and the outer crown area haveoutward convex surfaces separated by a trough region. 6 Headgearaccording to claim 5 wherein the outer crown area has a maximum heightgreater than the maximum height of the central crown area.
 7. Headgearfor protecting a wearer's skull including a generally bell-shaped shellof non-uniform thickness for enclosing at least an upper part of thewearer's skull, the shell having an upper crown portion having a centralcrown area and a surrounding outer crown area, the shell further havinga depending circumferential wall which has an upper wall area adjacentto the outer crown area and a lower wall area, said lower wall areahaving a wall thickness generally greater than the wall thickness ofsaid upper wall area and said central crown area having a wall thicknessgenerally greater than the wall thickness of said outer crown area, anda support system attached to the lower wall area of the shell, whereinin normal use the support system rests on the wearer's skull andmaintains an inside surface of the shell at least a predetermineddistance from the wearer's skull.
 8. Headgear according to claim 7wherein the predetermined distance is no less than 5 mm.
 9. Headgearaccording to claim 7 or claim 8 wherein the upper wall area has athickness greater than the thickness of the outer crown area. 10.Headgear according to any one of claims 7 to 9 wherein the central crownarea is generally depressed relative to the surrounding outer crown areaand includes a centrally located dome, the outer crown area forming acontinuous ridge around the central crown area.
 11. Headgear accordingto any one of claims 7 to 10 wherein the upper crown portion has athickness varying from 2.0+or −0.1 mm to 3.4+or −0.1 mm and thethickness of the circumferential wall varying from 2.6+or −0.1 mm to3.8+or −0.1 mm.
 12. Headgear according to any one of claims 7 to 10wherein the central crown area is between 2.4+or −0.1 mm and 3.4+or −0.1mm, the outer crown area is between 2.0+or −0.1 mm and 2.4+or −0.1 mmthick, the upper wall area is between 2.6+or −0.1 mm and 3.0+or −0.1 mmthick and the lower wall area is between 3.4+or −0.1 mm and 3.8+or −0.1mm thick.
 13. Headgear for protecting a wearer's skull including agenerally bell shaped shell of non-uniform thickness for enclosing atleast an upper part of the wearer's skull, the shell having an uppercrown portion with a depending circumferential wall area which has anupper wall area adjacent to the upper crown portion and a lower wallarea, said lower wall area having a wall thickness generally greaterthan a wall thickness of said upper wall area, and a support systemattached to the lower wall area of the shell, wherein in normal use thesupport system rests on the wearer's skull and maintains an insidesurface of the shell at least a predetermined distance from the wearer'sskull.
 14. Headgear according to claim 13 wherein said crown portion hasa wall thickness generally greater than a zone of said shell betweensaid upper crown portion and said upper wall area.
 15. Headgearaccording to claim 13 or claim 14 wherein the predetermined distance isno less than 5 mm.
 16. Headgear according to any one of claims 13 to 15wherein said zone has a thickness less than the thickness of said upperwall area.
 17. Headgear according to any one of claims 13 to 16 whereinthe thickness of said shell merges smoothly between the lower wall areaand the upper crown portion.
 18. A hat including the headgear of any oneof the preceding claims wherein the shell is enclosed within felt,cloth, leather or other material.
 19. A hat having an outer covering ofa flexible sheet material, a generally bell shaped shell moulded from ahigh impact resistant material, the shell having an upper crown portionwith a depending circumferential wall area adjacent to the upper crownportion, the shell being configured to fit within said outer covering,and a support system attached to a lower wall area of the shell, whereinin normal use, the system rests on the wearer's skull and maintains aninside surface of the shell at least a predetermined distance from thewearer's skull.
 20. A hat according to claim 19 wherein the shell is ofnon-uniform thickness.
 21. A hat according to claim 20 wherein thedepending circumferential wall area is formed by a first upper wall areaand a second lower wall area, the second lower wall area having athickness greater than said first upper wall area.
 22. A hat accordingto claim 20 or claim 21 wherein said upper crown portion has a wallthickness generally greater than a zone of said shell between said uppercrown portion and said depending circumferential wall area.
 23. A hataccording to claim 22 wherein said zone has a thickness less than thethickness of said depending circumferential wall area.
 24. A hataccording to any one of claims 19 to 23 wherein the predetermineddistance is no less than 5 mm.
 25. A hat according to any one of claims19 to 24 wherein the outer covering includes a said shell coveringportion and a wide surrounding brim formed at lower edge of said shellcovering portion.